Devices, methods and systems for establishing supplemental blood flow in the circulatory system

ABSTRACT

A blood circulation assist system comprising an inflow cannula having a lumen and an insertion device configured to be received therein and to facilitate insertion of a portion of the inflow cannula into a heart chamber. The insertion device includes a shaft having distal and proximal end portions and a plurality of lumens. A first lumen is configured to receive a guidewire and a second lumen is configured to receive a pressurized fluid. A tip connected to the distal end portion of the shaft is configured for insertion into the heart chamber. The tip has a hollow interior communicating with the first shaft lumen. An inflatable member is coupled to the distal end portion of the shaft and includes a hollow interior in fluid communication with the second shaft lumen. The inflatable member is movable between deflated and inflated configurations for releasably securing the insertion device to the inflow cannula.

CROSS REFERENCE

This application is a continuation-in-part of PCT Application Serial No.PCT/US07/76956 filed on Aug. 28, 2007 (pending) and claims the prioritybenefit of U.S. Provisional Patent Application Ser. No. 60/823,971,“Devices, Methods and Systems for Establishing Supplemental Blood Flowin the Circulatory System”, filed Aug. 30, 2006 (pending), thedisclosures of which are expressly incorporated by reference herein intheir entirety. This application is also generally related to co-pendingU.S. patent application Ser. No. 11/846,886, entitled “Cannula InsertionDevices, Systems, And Methods Including A Compressible Member”, filed oneven date herewith, which is expressly incorporated by reference hereinin its entirety.

TECHNICAL FIELD

This invention generally relates to medical devices and methods and,more particularly, to methods and devices for fluid coupling to theheart of a patient in systems for assisting blood circulation in apatient.

BACKGROUND

Various devices and methods have been utilized to conduct blood from theheart to assist with blood circulation in a patient. This is oftendesirable or necessary in cases where a patient is experiencingcongestive heart failure and a transplant organ has either not beenlocated, or the patient is not a suitable candidate for a transplant.The blood pumps are typically attached directly to the left ventricle ofthe heart, however, at least one blood pump system locates the pumpremotely, such as subcutaneously in the manner of a pacemaker. In thisregard, see U.S. Pat. No. 6,530,876, the disclosure of which is herebyfully incorporated by reference herein. In this situation or similarsituations, a cannula may be used to create an inflow conduit from theheart (an intra-thoracic location) to a pump located in a superficial(non-thoracic cavity) location, which may be the so-called “pacemakerpocket.” Of course, other remote locations are possible as alternatives.The pacemaker pocket is a location usually accessed by a surgicalincision generally parallel to and below the collarbone extending downtoward the breast, and over the pectoral muscle. Sometimes the pacemakerpocket is made below the muscle. The pump, to which the cannula isconnected, is intended to sit in the pectoral pocket and is preferablyat, but not limited to, a location on the right side of the chest.

One area in need of improvement is the insertion device, or trocar, usedto deliver an inflow conduit or cannula to the heart. It would bedesirable to provide an insertion device configured to give a surgeonenhanced control of the location of the tip of the insertion device tominimize trauma to the heart tissue during the process of inserting thetip of the insertion device through an incision or other opening in theheart tissue and into a chamber of the heart and to simplify thisprocedure resulting in a reduction in surgery time. It would also bedesirable to provide an insertion device that may be securely engagedwith the inflow cannula during insertion of the cannula into a chamberof the heart, and then disengaged from the cannula for removal.

General cannula implantation methods known and usable in connection withthe present invention may involve many different approaches and severalof the representative approaches are described further below. Forexample, the cannula may be implanted by directly invading the thoraciccavity. Surgical methods include so-called open heart surgery in which amedian sternotomy is made to fully expose the heart within the thoraciccavity. Still other surgical methods include less invasive surgicalmethods such as a thoracotomy, mini-thoracotomy, thoracoscopic, or anyother less invasive approaches. Any of these or other surgical methodscan be used to implant the cannula in fluid communication with anydesired location of the heart as described herein.

SUMMARY

Generally, and in one of many aspects, the present invention provides adevice for establishing a blood flow conduit between a chamber in aheart of a patient and a remote location, such as a location at which ablood pump resides away from the heart. In this regard, the term“remote,” as used herein means away from the heart but is not limited toany particular distance from the heart. The devices and systems of thepresent invention include an inflow cannula having a lumen, and aninsertion device configured to be received within the lumen of theinflow cannula and to facilitate insertion of a portion of the inflowcannula into the chamber of the heart. The insertion device has a shafthaving a distal end portion, and a proximal end portion (relative to asurgeon implanting the cannula) and a plurality of lumens formedtherein. A first one of the lumens is configured to receive a guidewiretherein and a second one of the lumens is configured to receive apressurized fluid therein. The insertion device further includes a tipconnected to the distal end portion of the shaft, with the tip beingconfigured for insertion into the chamber of the heart. The tip has ahollow interior communicating with the first one of the lumens of theshaft. The insertion device also includes an inflatable member coupledto the distal end portion of the shaft and having a hollow interior influid communication with the second one of the lumens of the shaft. Theinflatable member is movable between a first, deflated configuration anda second, inflated configuration for releasably securing the insertiondevice to the inflow cannula.

In other embodiments, the system may include one or more of thefollowing features. The system may further include a blood pump havingan inlet and an outlet and an outflow cannula coupled at one end thereofto the outlet of the pump and configured to be coupled, at an oppositeend thereof, to the arterial system of the patient. A proximal endportion of the inflow cannula may be coupled to the inlet of the bloodpump and the distal end portion of the inflow cannula is configured forinsertion into the chamber of the heart.

The insertion device may further include a hub connected to the proximalend portion of the shaft. The hub may include a first leg having a firstlumen formed therein that communicates with the first one of the lumensin the shaft, and a second leg having a second lumen formed therein andin fluid communication with the second one of the lumens of the shaft.The second leg may be configured for coupling to a source of fluid. Theshaft may further include an aperture formed in the distal end portionthat is in fluid communication with the second one of the shaft lumensand the hollow interior of the inflatable member, which may be agenerally cylindrical sleeve when inflated. In one embodiment, the shaftmay include three lumens, with one being configured to receive aguidewire therein and with the other two being in fluid communicationwith the hollow interior of the inflatable member. The shaft maycomprise inner and outer cylindrical extrusions connected by a pluralityof circumferentially spaced ribs.

In another aspect, the invention provides a system for inserting acannula through biologic tissue. The system includes a cannula having alumen and an insertion device configured to be received within the lumenof the cannula and to facilitate insertion of a portion of the cannulathrough the biologic tissue. The insertion device includes a shafthaving proximal and distal end portions and a tip connected to thedistal end portion of the shaft. The tip is configured for insertionthrough the biologic tissue. The system also includes an expandablemember coupled to the distal end portion of the shaft, with theexpandable member being movable between a first configuration whereinthe expandable member is disengaged with the inflow cannula, and asecond configuration wherein the expandable member is releasably securedto the inflow cannula.

In another aspect, the invention provides a method of inserting aninflow cannula having a lumen into a chamber in a heart of a patient.The method includes the step of inserting an insertion device into thelumen of the inflow cannula wherein at least a portion of a tip of theinsertion device protrudes beyond a distal end portion of the inflowcannula. The insertion device further includes a shaft, with the tipbeing secured to a distal end portion of the shaft, and an expandablemember coupled to the distal end portion of the shaft. The methodfurther comprises expanding the expandable member to releasably securethe inflow cannula to the insertion device and inserting the tip of theinsertion device and a distal end portion of the inflow cannula into thechamber of the heart.

In other embodiments, the method of inserting an inflow cannula into achamber of the patient's heart may include one or more of the followingsteps. The expandable member may be an inflatable member and the step ofexpanding may comprise inflating the inflatable member. This step mayinclude directing a pressurized fluid through a lumen formed in theshaft of the insertion device into a hollow interior of the inflatablemember. A puncture may be created in the tissue defining the chamber andthe puncture may be gradually dilated with the tip of the insertiondevice to a larger size to facilitate inserting the distal end portionof the inflow cannula into the chamber of the heart. The inflow cannulamay be secured to tissue of the heart defining the chamber and theexpandable member may be disengaged from the cannula after securing thecannula to the heart tissue.

In another aspect, the invention provides a method of inserting acannula having a lumen through biologic tissue. The method includes thestep of inserting an insertion device into the lumen of the cannulawherein at least a portion of a tip of the insertion device protrudesbeyond a distal end portion of the cannula. The insertion device furtherincludes a shaft, with the tip being secured to a distal end portion ofthe shaft, and an expandable member coupled to the distal end portion ofthe shaft. The method further includes expanding the expandable memberto releasably secure the cannula to the insertion device and insertingthe tip of the insertion device and the distal end portion of thecannula through the tissue.

Various additional features and aspects will be more readily appreciatedupon review of the following detailed description of the illustrativeembodiments taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of chest anatomy, and illustratesone example of a pathway, exterior to the venous system, used to accessa patient's heart and implant a circulatory assist system in accordancewith an embodiment of the invention.

FIG. 2 is a cross-sectional view of an inflow cannula with an insertiondevice according to an embodiment of the present invention extendingthrough a lumen of the inflow cannula, and with an inflatable member ofthe insertion device inflated to releasably secure the insertion deviceto the inflow cannula.

FIG. 3A is a cross-sectional view taken along line 3A-3A in FIG. 2A withthe inflatable member of the insertion device inflated.

FIG. 3B is a cross-sectional view taken along line 3B-3B in FIG. 7F withthe inflatable member of the insertion device deflated.

FIG. 4 is a cross-sectional view of the hub, and a portion of the shaft,of the insertion device shown in FIGS. 2, 3A and 3B.

FIG. 5 is a cross-sectional view of a shaft of an insertion deviceaccording to another embodiment of the present invention.

FIG. 6 is a cross-sectional view of a shaft of an insertion deviceaccording to another embodiment of the present invention.

FIG. 7A is an enlarged view of the heart illustrating an access locationto the interior of the heart.

FIG. 7B is a view similar to FIG. 7A, but illustrating the accesslocation exposed and generally showing an inflow cannula being directedtoward the access location with the insertion device and a guidewireextending beyond the distal end portion of the inflow cannula.

FIG. 7C is a fragmentary cross-sectional view of the heart illustratinga subsequent portion of the procedure, with the guidewire and a portionof a tip of the insertion device inserted into the left atrial chamberor left atrium of the heart, and with the inflatable member of theinsertion device inflated to releasably secure the insertion device tothe inflow cannula.

FIG. 7D is a fragmentary cross-sectional view similar to FIG. 7C,illustrating a subsequent portion of the procedure, with the entire tipof the insertion device and the distal end portion of the inflowcannula, including the distal element of the cannula, inserted into theleft atrium and with the associated purse string sutures loosened.

FIG. 7E is a fragmentary cross-sectional view similar to FIG. 7D,illustrating a subsequent portion of the procedure, but with the pursestring sutures tightened illustrating the gathering of tissue betweenthe proximal and distal anchor elements of the inflow cannula.

FIG. 7F is a cross-sectional view similar to FIG. 7E, illustrating asubsequent portion of the procedure, with the insertion device andguidewire in the process of being removed from the inflow cannula.

FIG. 7G is an enlarged view of the heart with the insertion device andguidewire removed and with the inflow cannula secured to the left atrialwall of the heart.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

FIG. 1 illustrates one of many possible general configurations of ablood circulation assist system 10 implanted in accordance with theinventive aspects. Devices and systems configured in accordance with theteachings herein may be implanted in any suitable surgical manner,including but not limited to those discussed generally herein, and maybe used to insert a cannula through heart tissue into a chamber of theheart. Devices and systems configured in accordance with the inventiveaspects may also be used to insert a cannula through other biologictissue, for example through kidney tissue into an interior chamber ofthe kidney.

System 10 includes an inflow cannula 12 that includes a distal endportion 12 a that passes into the left atrium 14 of the heart 15 ofpatient 20. Access may be made, for example, into any portion within theleft side of the heart (e.g., the left atrium and/or left ventricle) toaccess oxygenated blood. The inflow cannula 12 is attached directly toan exterior wall of the heart 15 on the left side, such as to the leftatrial wall 14 a as shown in FIGS. 7F-7G. The inflow cannula 12 may bedirected to the exterior area of the heart through any desired surgicalapproach, such as one of the approaches generally discussedsubsequently. Cannula 12 includes a distal anchor element 22 and aproximal anchor element 24 that have a disc-like configuration in theillustrative embodiment. However, anchor elements 22, 24 can have otherconfigurations, such as illustrated in previously referenced U.S. PatentApplication Ser. No. 60/823,971. Cannula 12 may be made of variousimplant or medical grade materials, such as silicone.

The blood circulation assist system 10 also includes a blood pump 30,having an inlet 32 and an outlet 34, and an outflow cannula 36. Aproximal end portion 12 b of inflow cannula 12 is coupled to the inlet32 of blood pump 30. Any suitable blood pump 30 may be used, includingthose described in U.S. Pat. Nos. 6,176,848; 6,116,862; 6,942,611; and6,623,475 or DE 10 2004 019 721.0. The outflow cannula 36 is connectedbetween the outlet 34 of the pump 30 and an artery, such as thesuperficial axillary artery 40. Blood flow therefore travels in thedirection of the arrows 42 from the left atrium 14, through the pump 30,and into the patient's arterial system through the outflow cannula 36.The outflow cannula 36 may be connected to a superficial artery, such asthe axillary artery 40, through a suitable surgical incision andattachment procedure which may involve the use of suitable grafts (notshown) and suturing (not shown).

The inflow and/or outflow cannulas 12, 36 may be connected to blood pump30 prior to or after implantation of pump 30. The inflow and/or outflowcannulas 12, 36 may first be cut to a suitable length by an appropriatesterilized cutting tool (not shown), such that the system may be moreeasily implanted into, for example, a pectoral pacemaker pocket withoutkinking of cannulas 12, 36 as illustrated in previously referenced U.S.Patent Application Ser. No. 60/823,971.

The inflow cannula 12 may be delivered to heart 15 using an insertiondevice 200 according to one embodiment of the present invention, inconjunction with any suitable surgical procedure. The insertion device200 has multiple functions associated with a cannula, such as inflowcannula 12. These functions include: provision of an expandable memberthat is used to releasably secure the insertion device 200 to a cannula,such as inflow cannula 12, which enhances the ability of a surgeon todeliver the cannula to a desired access location and to insert thecannula through biologic tissue, that may be heart tissue, whileminimizing trauma to the tissue due to the stiffness of the combinationof the cannula and the insertion device 200; and gradually dilating anopening in the tissue, such as a puncture or incision, to a larger sizeto facilitate inserting a distal end portion of the cannula through thebiologic tissue. One illustrative procedure is discussed subsequentlywith reference to FIGS. 2 and 7A-7G. FIGS. 2 and 7B-7E illustrateinsertion device 200 inserted into a lumen 16 of the inflow cannula 12,over a guidewire 50 with insertion device 200 releasably secured toinflow cannula 12.

Insertion device 200 includes a shaft 206 having a distal end portion208 (FIG. 2), a proximal end portion 210 (FIG. 4) and lumens 212, 214formed therein (shown in FIGS. 3A, 3B and 4). Lumen 212 is configured toaccept any commercially available guidewire therein, such as guidewire50. Lumen 214 is configured to receive a pressurized fluid therein,typically a sterile liquid, that may be received from a syringe, forexample, as discussed further in greater detail. Lumens 212, 214 do notcommunicate with one another. Shaft 206 may be made from materialshaving a high durometer. In one embodiment, these materials may have adurometer of 63 D or higher. Examples of suitable materials include, butare not limited to, thermoplastic materials such as nylon, urethane andPebax®. Any other suitable biocompatible material may be used to makeshaft 206.

Insertion device 200 further includes a tip 220 connected to the distalend portion 208 of shaft 206, a hub 222 connected to the proximal endportion 210 of shaft 206 and an expandable member 224 coupled to thedistal end portion 208 of shaft 206. In the illustrated embodiment,expandable member 224 is more particularly an inflatable member.However, as subsequently discussed in greater detail, other insertiondevices having different expandable members may be used in accordancewith the inventive aspects. Inflatable member 224 may extend at leastpartially around the distal end portion 208. Inflatable member 224 maybe a balloon-like expandable member as used, for example, inconventional balloon catheters. FIGS. 2, 3A, 7C, 7D and 7E illustratethe inflatable member 224 inflated, or expanded, which releasablysecures the insertion device 200 to inflow cannula 12. FIGS. 3B and 7Fillustrate the inflatable member deflated or collapsed so that insertiondevice 200 does not engage inflow cannula 12 and therefore is nottemporarily secured to inflow cannula 12.

Tip 220 includes a hollow interior 226 (FIG. 7C) that communicates withlumen 212 of shaft 206 to receive guidewire 50. An inside diameter oftip 220 is sized to accommodate a commercially available guidewire, suchas guidewire 50, and is typically larger than the outside diameter ofthe guidewire by about 0.003 inch or more. As subsequently discussedwith reference to FIGS. 7B-7E, the guidewire 50 protrudes beyond tip 220into chamber 14 of heart 15 during the initial steps of this procedure.Tip 220 is configured for insertion into chamber 14 of heart 15 and tofacilitate insertion of inflow cannula 12 into chamber 14. Theconfiguration of tip 220 causes a gradual dilation of an incision in theheart tissue, in this case the left atrial wall 14 a, to a larger sizethat is sufficient to receive the inflow cannula 12. This gradualdilation may be achieved by a tip such as tip 220 having a steppedconfiguration as shown in FIGS. 2 and 7B-7F, or alternatively, with atip (not shown) having a continuous taper. In either event, the tipconverges from a proximal end portion to a distal end portion.

Tip 220 may include tapered portions 230, 232 and cylindrical portions234, 236. Tapered portion 230 is a distal end portion of tip 220 in theillustrated embodiment and is integral with cylindrical portion 234.Tapered portion 232 is integral with cylindrical portion 234 andcylindrical portion 236, which is the proximal end portion of tip 220 inthe illustrated embodiment. Alternatively, the tip of insertion device200 may include additional tapered and cylindrical portions. Each of thecylindrical portions of tip 220, in this case cylindrical portions 234,236, has a unique outside diameter, with the outside diametersprogressively increasing in size from a distal most one of thecylindrical portions, in this case cylindrical portion 234, to aproximal most one of the cylindrical portions, in this case cylindricalportion 236. For example, cylindrical portion 234 has an outsidediameter d₁ and cylindrical portion 236 has an outside diameter d₂ thatis greater than d₁ (FIG. 7D). The number of tapers incorporated in thetip of insertion device 200 is dependent upon the inside diameter of theinflow cannula. In one embodiment, if the inside diameter of the inflowcannula, such as inflow cannula 12, is about 6 mm, the tip of insertiondevice 200 may include two tapers, such as tip 220. In this example, thediameter d₁ of the cylindrical portion 234 may be about 2 mm and thediameter d₂ of the cylindrical portion 236 may be about 4 mm. However,diameters d₁ and d₂ may have different magnitudes, depending upon theinside diameter of the inflow cannula, such as inflow cannula 12. If,for example, the anatomy is not large enough to support a tip having astepped configuration, such as tip 220, a tip (not shown) may beprovided with a continuous taper. For example, if the dimension across achamber of the heart (from location of entry to an opposite wall) intowhich a tip is to be inserted is less than the overall length of a tiphaving multiple tapers, then a shorter tip with one continuous taperwould be used.

Tip 220 may be made from a thermoplastic material, for example, nylon,urethane, or Pebax® and may include a filler material that isradiopaque, for example, barium or tungsten. The filler material may bea metallic paste. Tip 220 may also be made from any other suitablebiocompatible base and filler materials. Additional features, forexample, dimpling (not shown) may be added to tip 220 to enhance thevisibility of tip 220 if a transesophageal echocardiogram procedure orthe equivalent, is to be used during placement of the insertion device200.

As best shown in FIG. 4, hub 222 is configured to provide access to thelumens 212, 214 of shaft 206. In the illustrated embodiment, hub 222 hasa leg 240 that extends along the distal end portion 210 of shaft 206 andincludes a lumen 242 that communicates with lumen 212 of shaft 206.Accordingly, lumen 242 may receive the guidewire 50. Leg 240 of hub 222may include a luer thread 243 conforming to ISO 594 or an equivalent, topermit flushing of lumen 242 before and/or after use of insertion device200.

Hub 222 further includes a leg 244 that may be angled relative to leg240 and includes a lumen 246 that is in fluid communication with lumen214 of shaft 206, for purposes of inflating or deflating the inflatablemember 224. Shaft 206 includes at least one aperture 247, which may be anotch, formed therein proximate hub 222 to establish this fluidcommunication. Leg 244 is adapted for coupling to a source of fluid,typically a liquid such as a saline solution, which can be pressurized.This may be accomplished by providing a proximal end portion of leg 244with a luer thread 248 conforming to ISO 594 or an equivalent, toreceive a syringe 250. Lumen 246 of leg 244 of hub 222 is in fluidcommunication with a hollow interior of syringe 250, which is adapted tocontain fluid therein. An aperture 252, which may be a notch or skive,(FIGS. 3A and 3B) is formed in a portion of shaft 206 that is covered bythe inflatable member 224 and provides fluid communication between lumen214 of shaft 206 and a hollow interior 254 of inflatable member 224.

Hub 222 may be made from a material that is typically used for catheterapplications. Examples of suitable materials include, but are notlimited to, a polycarbonate and nylon. Hub 222 may also be made from anyother suitable biocompatible material. Hub 222 may be secured to shaft206 by an adhesive or other conventional means and is sized toaccommodate the outside diameter of the particular shaft to which it issecured.

The inflatable member 224 is typically positioned proximate tip 220, asillustrated in FIGS. 2, and 7C-7F, and may be secured to shaft 206. Anadhesive, a melting or welding process, or other suitable means orprocesses may be used to secure the inflatable member 224 to shaft 206.Inflatable member 224 is used to releasably secure the inflow cannula 12to the insertion device 200 when member 224 is inflated, in view of theflexibility of the inflow cannula 12, to assist a surgeon in directingthe inflow cannula to the desired access location on the heart 15. Thisprovides stiffness to at least a distal end portion 12 a of the inflowcannula 12.

The inflatable member 224 may be a generally cylindrical sleeve wheninflated. Inflation may be achieved by extending the plunger (not shown)of syringe 250, which pressurizes the fluid therein, causing the fluidto flow through lumen 246 of leg 244 of hub 222 and into lumen 214 ofshaft 206. The fluid then flows from lumen 214 through aperture 252 inshaft 206 and into the hollow interior 254 of inflatable member 224 asillustrated by arrows 262 in FIG. 3A.

The length of inflatable member 224, i.e., the longitudinal distancealong shaft 206, varies depending upon the desired stiffness of thedistal end portion 12 a of inflow cannula 12 and the associated contactsurface between the outer surface of inflatable member 224 and the innersurface of inflow cannula 12 when the inflatable member 224 is inflated.For example, the length of the inflatable member 224 may vary from about5 mm to about 50 mm, depending upon the particular application. Theoutside diameter of inflatable member 224, when member 224 is inflated,may be sized to provide about 0 to about 1 mm of interference with theinner surface of inflow cannula 12.

Inflatable member 224 may be made from a thermoplastic material, forexample nylon, PET, polyethylene, polyurethane or Pebax®. Inflatablemember 224 may also be made from any other suitable biocompatiblematerial. The material used to make inflatable member 224 typically hasa rated burst pressure of at least 2 atm. The wall thickness ofinflatable member 224 for the particular length of inflatable member 224is directly related to the desired burst pressure, the materialproperties and the inflation diameter of inflatable member 224. Hooke'sLaw for thin-walled cylinders may be used to determine the wallthickness of inflatable member 224.

After the distal end portion 12 a of the inflow cannula 12 is insertedinto chamber 14 at the desired position and is secured to the heart 15with purse string sutures, for example, the inflatable member 224 isdeflated. Deflation may be achieved by retracting the plunger of syringe250 which causes the fluid to flow from the hollow interior 254 of theinflatable member 224 back into syringe 250. The volume of the lumen 214in shaft 206 is sized to permit the inflatable member 224 to be inflatedand deflated within an acceptable time period, for example, about 30second or less. After inflatable member 224 has been deflated, theinsertion device 200 may be withdrawn from the inflow cannula 12.

FIG. 5 illustrates an insertion device 200 a that is the same asinsertion device 200 except that insertion device 200 a includes a shaft270 instead of shaft 206 of insertion device 200. Shaft 270 includes alumen 271, similar to lumen 212 of shaft 206, to accept guidewire 50.Instead of a relatively larger, outer lumen such as lumen 214 in shaft206, shaft 270 includes two relatively smaller outer lumens 272,separated by a rib 274 that extends along the length of shaft 270. Eachof the lumens 272 is in fluid communication with the hollow interior 254of the inflatable member 224 and the source of pressurized fluid, inthis case syringe 250. Shaft 270 includes the appropriate apertures,which may be notches or skives (not shown), in the proximal and distalend portions to provide fluid communication between the lumens 272 andthe lumen 246 of leg 244 of hub 222 and the hollow interior 254 of theinflatable member 224, respectively. Incorporation of rib 274 enhancesthe structural characteristics of shaft 270.

FIG. 6 illustrates an insertion device 200 b that is the same asinsertion device 200 except that insertion device 200 b includes a shaft280 instead of shaft 206 of insertion device 200. Shaft 280 includes aninner 282 and outer 284 cylindrical extrusions that are concentricallypositioned and interconnected by a plurality of circumferentially spacedribs 286. Extrusions 282, 284 and ribs 286 define outer lumens 288. Eachof the outer lumens 288 is in fluid communication with the hollowinterior 254 of the inflatable member 224, and the source of pressurizedfluid, in this case syringe 250. Shaft 280 includes the appropriateapertures, which may be notches or skives (not shown), in the proximaland distal end portions to provide fluid communication between lumens288 and the lumen 246 of leg 244 of hub 222 and the hollow interior 254of the inflatable member 224, respectively. Shaft 280 further includesan inner lumen 290 to receive guidewire 50.

Another alternate insertion device (not shown) may be similar toinsertion device 200 but may further include a stiff hypotube thatsurrounds a multi-lumen inner shaft made of a more flexible materialsuch as thermoplastic material. The hypotube may be made of metal, forexample, stainless steel. The hypotube increases the column strength ofthe insertion device relative to a device such as insertion device 200.The alternate insertion device may further include an inner strainrelief and an outer strain relief. The inner strain relief may be addedto the construction to provide a barrier between the multi-lumen innershaft and the hypotube while providing a stiffness transition proximalto the included inflatable member. The inner strain relief is typicallya thin-walled tube and may be made from a thermoplastic material, forexample, Pebax, nylon or polyurethane, but may also be made from aheat-shrink tube, such as a polyester tube. The inner strain relief maybe secured to the hypotube at its most proximal end (e.g., near theincluded hub of the insertion device) and this may be accomplished bythe use of an adhesive or heat melting process, for example. Typically,the distal end of the inner strain relief is not secured in place. Thisallows for relative movement between the multi-lumen inner shaft and theinner strain relief if the insertion device is placed into a curveduring insertion. The outer strain relief may extend distal to thehypotube and terminate proximal to the distal end of the inner strainrelief. This positioning provides a stiffness gradient from the stiffestcomponent of the insertion device, i.e., the hypotube, to the mostflexible component, i.e., the multi-lumen inner shaft. The outer strainrelief may be made from a thermoplastic material, such as Pebax, nylonor polyurethane, but may also be made from a heat shrink tube, such aspolyester or polyolefin tube. Incorporation of the inner and outerstrain reliefs help prevent kinking of the insertion device at locationstransitioning from a relatively larger diameter component to arelatively smaller component.

One illustrative procedure for connecting the inflow cannula 12 to heart15 is shown in FIGS. 7A-7G. In this regard, an access location 300 (FIG.7A) such as the so-called Waterson's groove is exposed or otherwiseaccessed during a surgical procedure. A puncture 302 (FIG. 7B) may bemade in wall 14 a of heart 15 at the access location 300 with a hollowneedle 304 to access the interior of the left atrium 14 to allow for theinsertion of the distal end portion 12 a of cannula 12. In alternatesurgical procedures a small incision may be made with a scalpel, in lieuof puncture 302 made with needle 304, to access the interior of the leftatrium 14. The diameter of the lumen of needle 304 must be large enoughto allow passage of guidewire 50 through needle 304.

FIG. 7B illustrates inflow cannula and insertion device 200 delivered toa location proximate heart 15, with guidewire 50 inserted throughpuncture 302 into the left atrium 14. The guidewire 50 is typicallylooped within atrium 14 to help avoid any trauma to the heart tissue bythe distal tip 50 a of the guidewire 50. As shown in FIGS. 7C-7F, one ormore purse string sutures 306, 308 may be secured around the puncture302 in preparation for the insertion of cannula 12.

FIG. 7C illustrates the step of advancing the tip 220 of insertiondevice 200 across the left atrial wall 14 a over the guidewire 50. Theinflatable member 224 is inflated during the steps illustrated in FIGS.7C-7E to temporarily and releasably secure the insertion device 200 toinflow cannula 12. The stiffness of insertion device 200 permits thesurgeon to deliver the insertion device 200 and inflow cannula 12accurately to the access location 300 and to insert the tip 220 ofinsertion device 200 through puncture 302 while minimizing trauma to theheart tissue. Inflatable member 224 can remain inflated until sutures306, 308 are tightened as subsequently discussed.

FIG. 7D illustrates a subsequent step with the entire tip 220 ofinsertion device 200, the distal end portion 12 a of cannula 12, and thedistal anchor element 22 of cannula 12 inserted into the left atrium 14.In some procedures, the inflow cannula 12 may be inserted into leftatrium 14 such that the distal and proximal anchor elements 22, 24 areinitially inserted into the left atrium 14. In this instance, the inflowcannula 12 is then withdrawn slightly proximally (toward the surgeon) toposition the proximal anchor element 24 outside the left atrium 14 whileleaving the distal anchor element 22 inside the left atrium 14, as shownin FIG. 7D. The material of the anchor elements 22, 24 may be a pliableand/or resilient material such as surgical grade silicone or any othersuitable biocompatible material. The anchor elements 22, 24 may collapsewhen passing through wall 14 a of heart 15, and may expand to theiroriginal shape once inserted into the left atrium 14 due to thecharacteristics of the material of anchor elements 22, 24.Alternatively, the anchor elements 22, 24 may be expanded or collapsedby any suitable mechanism operated by the surgeon. Additionally, theproximal anchor element 24 may have a smaller diameter than the distalanchor element 22, so that the smaller proximal anchor element 24 maynoticeably pop through puncture 302 leaving the distal anchor element 22as a firm stop against the opposite side of wall 14 a of heart 15, whichprovides perceptible feedback to the surgeon.

At this time, the purse string sutures 306, 308 may be tightened, asillustrated in FIG. 7E and tied off to fully secure the tissue 310between the distal 22 and proximal 24 anchor elements to provide a fluidtight or at least a substantially fluid tight seal. In this regard, thetightened tissue 310 should at least substantially fill or gather withinthe gap between the distal and proximal anchor elements 22, 24 as shownin FIG. 7E. If additional gathering of tissue 310 is necessary,additional tissue 310 may be gathered with one or more additional pursestring sutures. Anchor elements 22, 24 and the portion of cannula 12that engages wall 14 a may be provided with a tissue ingrowth materialto further aide in providing a leak tight seal.

After the sutures 306, 308 are tightened, guidewire 50 and insertiondevice 200 may be withdrawn as shown in FIG. 7F, leaving the distal endportion 12 a of cannula 12 inserted in left atrium 14 and with cannula12 secured to wall 14 a of heart 15 as shown in FIGS. 7F and 7G.

Co-pending U.S. patent application Ser. No. 11/846,886, entitled“Cannula Insertion Devices, Systems, and Methods Including aCompressible Member,” which is expressly incorporated by referencedherein in its entirety as noted previously, describes a sealing functionof the compressible member 116 of insertion device that advantageouslyprotects against blood loss and/or air ingress into the blood. This samefunction may be achieved with the inflatable member 224 of insertiondevice 200 disclosed herein. More specifically, when the inflatablemember 224 is sufficiently inflated, it provides a seal with the innersurface of inflow cannula 12. Accordingly, the inflatable member 224prevents blood loss through inflow cannula 12 when the distal endportion 12 a of cannula 12 is inserted into the left atrium 14 and thepurse string sutures 306, 308 are tightened to secure cannula 112 to theleft atrial wall 14 a as described above with reference to FIGS. 7D and7E.

Additionally, during the process of withdrawing the insertion device 200from inflow cannula 12, the inflatable member 224 may be partiallydeflated so that it remains in contact with the inner surface of cannula12 but allows insertion device 200 to slide relative to cannula 12(unlike FIG. 7F in which the inflatable member 224 is deflated so thatit does not engage the inner surface of cannula 12). In this event, theinsertion device 200 acts like a piston that removes air. In particular,the insertion device 200 may create a vacuum as it is retracted to drawblood from heart 15 into the inflow cannula 12. The blood replaces airthat previously occupied the inflow cannula 12.

Below, and as representative and nonlimiting examples, various surgicalapproaches are more fully described and may be used to practice thevarious aspects described hereinabove.

Surgical Open Sternotomy—This approach allows full access to the heart,especially the left atrium, and allows access to several differentlocations where a blood inflow cannula might be attached to the heart.However, due to the highly invasive nature of this approach, lessinvasive implantation approaches may be more desirable to a surgeon.

Surgical Open Thoracotomy—In this surgical approach, a relativelysuperior and caudal thoracotomy access is used to deliver the bloodinflow cannula to the left atrium where it is anchored. This location onthe atrium has specific benefit because the wall of the atrium is smoothand relatively large at this location, isolating the cannula tip fromother structures within the atrium.

In another suitable surgical method, a relatively lateral thoracotomyaccess is used to deliver the blood inflow cannula to the left atriumwhere it is anchored at a location on the postero-medial wall near theinteratrial septum. This location is often called “Waterson's groove” asdiscussed above and is a common location to make a left atriotomy whenperforming mitral valve repair surgery. Waterson's groove terminatesbetween the superior vena cava and the left pulmonary veins at the leftatrium.

Thoracoscopic Surgery—In this surgical method, the blood inflow cannulamay be implanted in a similar location as described above in that atubular trocar may be used to access the intra-thoracic location(Waterson's groove, for example) where the cannula would be anchoredthrough the heart wall. In this minimally or less invasive surgicalmethod, the entire operation is performed through these relatively smalltubular trocars thereby minimizing the size of the opening in thepatient's chest. Typically, additional small holes are made to delivertrocars used in conjunction with the main delivery trocar to allowplacement of an endoscopic camera and specialized surgical tools forgrasping, cutting, suturing, cauterizing, or performing other operationson tissue. Through the main trocar, the cannula can be delivered to thesame location as in the open surgical technique (i.e. Waterson's groove)but with less invasive access across the chest wall.

Over-the-Wire (Seldinger) Technique

A variation of the Seldinger technique might be utilized in the varioussurgical implantation approaches described above, where the cannulasystem would be specifically adapted to facilitate this implantationtechnique. Although the Seldinger technique is most commonly associatedwith percutaneous access to blood vessels, an adapted version of thetechnique utilizing a specifically adapted cannula introduction systemis a highly preferred approach to surgical implantation where directaccess to the heart itself is utilized. Here, for example, inserting aneedle across the heart wall could make an atriotomy and a guidewirecould then be placed therethrough. After removal of the needle, withbleeding controlled and minimal, the cannula system with specializedintroduction obturator within can be introduced over the wire therebymaintaining many of the advantages of the so-called Seldinger techniqueeven in a surgical approach.

While the present invention has been illustrated by a description ofvarious illustrative embodiments and while these embodiments have beendescribed in some detail, it is not the intention of the Applicants torestrict or in any way limit the scope of the appended claims to suchdetail. The features and aspects discussed herein may be used in anysuitable combination. Additional advantages and modifications willreadily appear to those skilled in the art. For example, although theinsertion devices disclosed in the embodiments illustrated hereininclude an inflatable member to releasably secure the respectiveinsertion device to a cannula, alternate insertion devices having otherconfigurations including other expandable members, which are notinflatable members, may be used according to the inventive aspects totemporarily and/or releasably secure the insertion devices to arespective cannula. Examples of such insertion devices are disclosed inpreviously referenced, co-pending U.S. patent application Ser. No.11/846,886, wherein the included expandable member is compressiblemember 116. Compressible member 116 expands radially outward whencompressed in an axial direction to releasably secure the respectiveinsertion device to a cannula. Any other suitable expanding member maybe used to secure the associated insertion device to a cannula. Also,tip 220 may be used with other insertion devices. For example, tip 220may be used with insertion devices that do not include inflatable member224 and/or hub 222. The various features of the invention may be usedalone or in any combinations depending on the needs and preferences ofthe user. However, the invention itself should only be defined by theappended claims.

1. A blood circulation assist system for increasing blood flow between achamber in a heart of a patient and a remote location in the circulatorysystem of the patient, the system comprising: an inflow cannula having alumen; and an insertion device configured to be received within thelumen of the inflow cannula and to facilitate insertion of a portion ofthe inflow cannula into the chamber of the heart, wherein the insertiondevice comprises: a shaft having a distal end portion, a proximal endportion and a plurality of lumens formed therein, a first one of thelumens being configured to receive a guidewire therein and a second oneof the lumens being configured to receive a pressurized fluid therein; atip connected to the distal end portion of the shaft, the tip beingconfigured for insertion into the chamber of the heart, the tip having ahollow interior communicating with the first one of the lumens of theshaft; and an inflatable member coupled to the distal end portion of theshaft and comprising a hollow interior in fluid communication with thesecond one of the lumens of the shaft, the inflatable member beingmovable between a first, deflated configuration wherein the inflatablemember is disengaged with the inflow cannula and a second, inflatedconfiguration wherein the insertion device is releasably secured to theinflow cannula.
 2. The system of claim 1, wherein the insertion devicefurther comprises: a hub connected to the proximal end portion of theshaft, the hub comprising a first leg having a first lumen formedtherein that communicates with the first one of the lumens of the shaft,the hub further comprising a second leg having a second lumen formedtherein and in fluid communication with the second one of the lumens ofthe shaft, the second leg being configured for coupling to a source offluid.
 3. The system of claim 2, wherein: the shaft further comprises anaperture formed in the distal end portion and in fluid communicationwith the second one of the lumens of the shaft and the hollow interiorof the inflatable member.
 4. The system of claim 1, wherein: the tip hasa stepped configuration.
 5. The system of claim 1, wherein: theinflatable member is a generally cylindrical sleeve when inflated. 6.The system of claim 1, wherein: the shaft further comprises a third oneof the lumens, the hollow interior of the inflatable member being influid communication with the second and third ones of the lumens.
 7. Thesystem of claim 1, wherein: the shaft further comprises inner and outercylindrical extrusions connected by a plurality of circumferentiallyspaced ribs.
 8. The system of claim 1, further comprising: a blood pumphaving an inlet and an outlet; and an outflow cannula coupled at one endthereof to the outlet of the blood pump and configured to be coupled, atan opposite end thereof, to an artery of the patient; wherein theproximal end portion of the inflow cannula is coupled to the inlet ofthe blood pump, the distal end portion of the inflow cannula beingconfigured for insertion into the chamber of the heart.